siemens transformer technology seminar low noise...

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Siemens Transformer Technology SeminarLow Noise Transformers

Pomona, CA May 24 – 25, 2016

Siemens AG – Transformers

© Siemens AG 2016 All rights reserved.

Low Noise TransformersGeneral

Various Noise Component Contributions

Kurt Kaineder - EM TR MPT GTC

No-Load Noise



Low noise design has several cost implications:

• Reduce no-load noise:• Core flux density may be reduced (larger core)

• Reduce wide spectrum (white) noise:• Use low-speed cooling fans, low noise pumps

• Reduce load noise:• Lower current density may be required (larger windings)• Special winding arrangements may be required• Sound absorbing panels or stiffened tank may be required




Examples: Low Noise Design




Basics:• Sound Emission

• Vibrating surface• Emission of sound power

• Sound propagation• Air particle oscillation / air pressure variation• Propagation as a wave

• Sound reception• Eardrum and diaphragm

or condenser microphone are sensitivefor air pressure variation



Low Noise TransformersBasics

Sound Emission

Total acoustic power is emitted by the sound source.Emitted sound - generated by transformer sound sources & independent of

distance.




Low Noise TransformersStandard

Standard: IEEE C57.12.90-2010 Chapter 13. Audible sound emissionsMeasurement principles are defined.

Microphone positions:• Interval 1m (3ft)• Distance from sound

producing surface• 0.3m (1f) w/o fans• 2.0m (6ft) with fans

• Height 1/3 and 2/3


Source IEEE C57.12.90


Low Noise TransformersStandard

Standard: IEEE C57.12.90-2010 Chapter 13. Audible sound emissionsMeasurement principles are defined.

Average sound pressure level (Lp) measurement:• The logarithmic sum of all at all microphone positions and all frequencies (A-

weighted)

= 10 ∙1

10

•Li…sound pressure measured and A-weightedN…# of positions

Sound power level calculation (Lw):Should be calculated out of the sound pressure data

= + 10 ∙ ( )S…measurement surface



Low Noise TransformersBasics

Ear ≠ linear microphone

dB(A) roughly corresponds to human ear’s equal-loudness curve.note: valid for < 55DB (at 1 kHz)

dBA-filtered sound level - less sensitive to very high & very low frequencies.dB(C) corresponds to ear’s equal-loudness curve for < 85dB



Low Noise TransformersBasics of Sound Propagation

Basic equations:Sound pressure levels vary substantially w/distance from source.

Multiple sources (direct & indirect) can contribute to measurements.

So distance doubled => sound pressure halved ( -6 dB)Distance *10 => sound pressure is 1/10 (-20 dB)Distance *30 => sound pressure is 1/30 (-30 dB)



Low Noise TransformersNo-Load Noise

Main influence parameters




Cost vs No-load Losses vs Noise

Influence of sound level on the costs of core sheets


sound level in dB(A) costs of sheets in %



R&D and engineering activities• Cooperation with leading core steel suppliers – development and specification

of new low noise material – test trials on transformers• Bar code/recording of exact test values of core material – steel of each core

stored in database and used for precise evaluations of noise performance• Large no-load noise database - characteristic curves for each power

transformer built in STA Weiz and Linz• Calculation of spectral no-load noise• Siemens has compiled a large no-load noise database• Predetermination of core resonances• Steady improvement and adjustment of models




Core measurement

Noise and core vibration• Core in air• Core in oil filled tank




Core Vibration and Core Noise


Transversal,

dominant in air

Axial - longitudinal


Low Noise TransformersAdditional Sources

Cooling Sound Reductions & Elimination of AuxiliarySound SourcesSiemens R&D and engineering activities:

• Collaboration with manufacturers of fans and pumpsto improve noise performance

• Maintenance of catalogs for fans and pumps(mechanical design department)

• Mechanical, electrical and chemical investigationson new materials for vibration isolation, vibrationdamping and sound panels

• Noise performance tests different noise damping methods• Extension of noise reduction catalog with new noise damping methods


Spectral Noise


Low Noise TransformersLoad Noise

Main influence parameter




Radial Winding Vibration – Effective Stiffness


Calculated

vibration mode (3D)

Measured

vibration mode

Winding in hydraulic press

Excited by impulse-hammer

Measurement of vibration



Calculation of load noise• Large spectral load noise database• Special dynamic calculation method• Winding properties and current harmonics• Avoidance of winding resonances• 3D Sound propagation simulation

R&D activities:• Continuous monitoring of load noise

calculations and measurements• Extension of large spectral load noise database

And now, the focus is on actual sound reduction methods



Low Noise Transformers3D Analysis 420 MVA

Sound Source / Sound Propagation

Sound propagation through oil, tank and air


← Sound source: axial & radial winding-vibrations


Low Noise TransformersOverview


No-Load Noise

• Vibration isolation• Noise reduction up to 4 dB(A)

• Sound panels• Noise reduction up to 12 dB(A)

• Sound enclosure• Noise reduction up to 30 dB(A)


Low Noise TransformersNoise Reduction Measures

Possible Sources of Sound ReductionAPPROACH ESTIMATED SOUND

REDUCTION, dB (A)

Reduced Core Flux Density 0 – 14 dB

Higher Quality Core Steel 0 – 6 dB

Reduced Load Noise 0 – 10 dB

Internal Attenuation 1 – 7 dB

Tank-supported Barriers 5 -11 dB

Free-standing Enclosure 15 -30 dB



Low Noise TransformersSuccessful Low Noise Transformer Design

Standard Design vs. Low Noise Design – 420 MVA


conditionstandard design

dB(A)low noise design

dB(A)noise reduction

dB(A)

no-load 100% Urated 65.5 46.5 - 19.0

load current 100% Irated 70.3 51.1 - 19.2

cooler fans, pumps 74.5 39.2 - 35.3

TOTAL 76.3 52.4 - 23.9



References LPT – as of 2010




MPT Reference projects

Total noise ~ 52dB




MPT Reference projects

no-load 44dB

over excitation17.6% 51dB

total @ 150MVA54dB



Low Noise TransformersLPT Masterpiece

Successful Low Noise Transformer DesignLow Noise Masterpiece

420 MVA• Standard design: 76.3 dB(A) sound pressure level• Low noise design: 52.4 dB(A) sound pressure level• Noise reduction: - 23.9 dB → For the human ear this is

4 times quieter!



Siemens AG – MPT TransformersContact

Kurt KainederHead of EngineeringHead of Electrical Design GlobalTechnology Center MPTSiemens AG Oesterreich

Transformers Linz

Kraussstraße 74020 LinzPhone: +43 (5) 1707-71098Fax: +43 (5) 1707-55391

Mobile: +43 (664) 615 4946Mobile: +43 (664) 80117 71098

E-mail: [email protected]

siemens.com/answers

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Siemens US – TransformersContact

James McIverPrincipal Application EngineerE T TR US6860 Bermuda Road, STE 100Las Vegas NV 89119USA

Mobile: (702) 241-0157

E-mail:[email protected]

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siemens transformer technology seminar low noise...

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